Clinical evaluation of patients in an Intensive Care Unit (ICU) often relies on diagnostic images, such as portable chest radiographic images, for example. It has been noted that chest radiographs can be helpful in the ICU for indicating significant or unexpected conditions requiring changes in patient management. To meet the need for readily accessible and rapid diagnostic imaging, equipment such as portable chest radiography equipment has been developed, allowing the ICU clinician to conveniently obtain a radiographic image as needed for the patient.
Patient treatment includes the ability to detect the proper positioning of the tip of a tube that has been inserted into the patient. Possible tube types include, for example, endo-tracheal (ET) tubes, feeding (FT) tubes, and nasogastric (NGT or NT) tubes. Proper tip positioning can help to insure delivery or disposal of liquids and gases to and from the patient during a treatment procedure. Improper tip positioning, on the other hand, can cause patient discomfort, can render a treatment ineffective, or can even be life-threatening.
Detecting proper ET tube position using automated image analysis tools has proved to be challenging. Some suggest that a preferred position of the ET tube within the trachea is approximately 3-4 cm above the carina trachea that lies between the openings of the right and left principal bronchi. Flexion and extension of the patient's neck can result in ET tip migration and malpositioning. When the ET tube is malpositioned within a mainstem bronchus, complete atelectasis of the contralateral lung is likely, accompanied by difficulties with mechanical ventilation. When the ET tube is malpositioned within the superior trachea, there is a risk of accidental extubation and vocal cord injury. According to one study, ET tube malpositioning occurs in approximately 15% of patients. The use of routine post-intubation chest radiography has been recommended for detection of ET tube malpositioning for which clinical diagnosis is unreliable, since it is often difficult to identify specific pulmonary complications on the basis of clinical examination alone.
Reliable detection and identification of ET tube tip positioning can be achieved when the carina can be accurately identified. However, the carina is often masked by other details of surrounding anatomy, so that it can even be difficult to detect the carina visually in a chest x-ray. Automated detection can be even more challenging; techniques for computer-assisted carina detection have proved to be error-prone and often less accurate than desirable, making tube and tip malpositioning difficult to detect in some cases.
Thus, there is a need for a detection method with improved accuracy for locating internal structures such as the carina in a digital radiographic image.